GF82.95-P-3000CAU Position Finding, Function

GF82.95-P-3000CAU Position Finding, Function
MODEL 207.3 /4
- with CODE (359) TELE AID emergency call system

Function requirements for position finding, general
^ Emergency call system is authorized
^ An emergency call system control unit (N123/4) communication module authorized for the corresponding vehicle-related service is configured ex-factory with the telephone number of the corresponding service provider

Position finding, general
The emergency call system control unit uses the satellite- supported global positioning system (GPS) to find its location. It is available worldwide.
The GPS satellites permanently transmit time and position data (longitude and latitude). GPS position finding is irretrievable after vehicle transport (e.g. by train or ferry or after towing). Relocation with GPS (after interruption of satellite reception) may require several minutes (up to t = 20 min when emergency call system control unit is operated for the first time).
Basic position finding runs parallel to GPS position finding.
The position finding function consists of the following component functions:
^ Function sequence for GPS position finding
^ Function sequence for basic position finding

Additional function requirements for GPS position finding
^ Circuit 15R ON or triggering of one of the following vehicle- related services:
- Manual or automatic emergency call, including police emergency call number "911"
- MB-Info call
- Breakdown assistance
- Vehicle tracking
- Vehicle remote door unlock
- Vehicle remote door lock
^ No fault in the GPS antenna system and signals from at least three GPS satellites

Function sequence for GPS position finding
The GPS receiver integrated into the emergency call system control unit receives the GPS signals from the multifunction antenna (A28/11) in the following way:
- Direct line
- Global positioning system antenna splitter (A2/5) (with code (512) COMAND APS with DVD changer or with code (527) COMAND APS with single DVD drive (with navigation)) and direct line
The GPS signals are used by the emergency call control unit to calculate the current vehicle position (receiver).
In addition, the vehicle's direction of travel is determined with the aid of the sequence of the locations calculated with GPS.

Additional function requirement for basic position finding
^ Status circuit 15R ON

Function sequence for basic position finding
For basic position finding, the emergency call control unit requires the following information:
- Wheel speed signals
- Distance traveled data
- Direction of travel data (forwards or backwards)
The wheel speed signals are recorded by the following components:
- Left front axle rpm sensor (L6/1)
- Right front axle rpm sensor (L6/2)
- Left rear axle rpm sensor (L6/3)
- Right rear axle rpm sensor (L6/4)
The wheel speed signals from the rpm sensors are received by the emergency call system control unit in the following way:
- Direct line
- Electronic Stability Program control unit (N30/4) (without code (233) DISTRONIC PLUS) or the Premium Electronic Stability Program control unit (N30/7) (with code (233) DISTRONIC PLUS).
- Chassis CAN (CAN E)
- Front SAM control unit with fuse and relay module (N10/1)
- Diagnostic CAN (CAN D)
The distance traveled data from the instrument cluster (A1) is received by the emergency call system control unit in the following way:
- Interior CAN (CAN B)
- Front SAM control unit
- Diagnostic CAN
The emergency call system control unit receives the data on the direction of travel (forwards or backwards) from the front SAM control unit over diagnosis CAN.
After this the emergency call system control unit uses the distance traveled, the vehicle alignment and the direction of travel to calculate the vehicle position (degree of longitude and degree of latitude) at any given time.
Error during position finding
Rolling backwards with "Circuit 15 OFF" (ignition switched off) or transport of the vehicle falsify the basic position finding. In both instances, the deviation is automatically corrected by the navigation processor integrated into the emergency call system control unit when it receives GPS data.